1. Field of the Invention
This invention relates to the construction of stringed musical instruments which employ a bridge in conjunction with a saddle, more particularly the specific structures associated with securing the strings over the sounding board diaphram and the coupling of the string vibrations thereto.
2. Description of Prior Art
In the conventional construction of an acoustical guitar, the strings are affixed to a carrier structure which is directly mounted upon the sounding board of the instrument with the strings rigidly positioned to make contact with a bridge element attached to a saddle which is, in turn, mounted to the sounding board. Vibrations induced in the strings are coupled into the sounding board via the bridge and saddle. In the present designs, the tensile loads, carried by the strings, are transmitted through the carrier to the sounding board which results in undesirable dampening of the diaphram action of the sounding board by virtue of the forces applied thereto and also as a consequence of the structural reinforcement necessary to prevent physical distortion of the sounding board by the applied tensile loading of the tuned strings.
One means for elimination of these dampening forces is, to some extent, described in U.S. Pat. No. 519,416 (issued May 8, 1894 to Robert L. Turner) for Tailpiece for Musical instruments wherein the carrier structure is affixed to the interior of the instrument and extends through two uncompensated apertures in the sounding board. The extremity of the described carrier, located at the exterior of the sounding board, supports and terminates the strings, while the bridge and saddle are of ordinary construction, with the exception that no provision is made for the usual termination and support of the strings in the saddle and that the protruding extremity of the carrier structure is separated from the bridge and saddle. The device as described by Turner possesses three distinct disadvantages, each of which are overcome by the present invention.
The first of these disadvantages relate to the method by which the adjustment of the coupling force between the strings and the sounding board is accomplished. In Turner, this adjustment is effected by the unaided human hand without any precision mechanism which would provide continuous positive adjustment with the mechanical advantage necessary to overcome the string loading of a tuned instrument. This constitues a serious deficiency in that this adjustment would require mechanically-aided precision in order to optimize the transfer of energy between the strings and the sounding board without the introduction of dampening forces resulting from the application of an excessive coupling force. Such excessive coupling forces are particularly detrimental in that they are applied at the source of vibration, i.e. where the strings come in contact with the bridge, and impede the freedom of motion of the sounding board. In contrast, a coupling force of insufficient magnitude results in an incomplete transfer of energy from the strings to the sounding board. The present invention incorporates the use of a device which provides a mechanical advantage with the precise positive adjustment necessary to optimize the coupling force applied to the bridge.
The second disadvantage associated with the device described in U.S. Pat. No. 519,416 relates to the extension of the carrier through the sounding board outside of the saddle structure. The aperture or orifices in the sounding board necessary for the carrier extension will, in themselves, serve as sources of undesirable distortions in the production of musical sound when they are displaced from the boundary of the saddle.
In the sounding board of an acoustical guitar of conventional construction, each note produces resonant nodes of vibration originating at a particular location on the sounding board that are uniquely determined by the frequency of the note. Evidence of this is shown in the reconstructed time-average holographic interferograms of the top plate of a typical guitar as provided in The Journal of the Acoustical Society of America, Volume 63, No. 5, page 1567; it is further illustrated by these holograms that the saddle contributes its own unique component in the formation of these nodes and will not, an any manner, serve to distort them or the sounded notes to which they are interrelated. Based upon such investigation, it is to be noted that a carrier, which supports the strings independently of the sounding board, would be contained within the saddle structure as provided by the present invention in order to preclude the formation of distortion sources.
A more simplified, but equally convincing, illustration of the foregoing is provided by considering the analogy between the sounding board of an acoustic guitar with its saddle as driving member and a loudspeaker diaphram with its own central circular driving member. Just as an orifice within the boundary of the central circular driving member of a loudspeaker will produce no distortions by virtue of its location within the source of vibrations, an analogous situation exists with an orifice contained within the boundary of an acoustic guitar's saddle which serves, in a like manner, as its source of vibrations. Similarly, a perforation in the exterior of the boundary of the central circular driving member of a loudspeaker will, in fact, produce sound distortions as will also occur in the case when an orifice exists in the exterior of the boundary formed by the saddle on the surface of the sounding board of an acoustical guitar. As stated earlier, this is overcome in the present invention by incorporating the carrier extension within the saddle structure.
A final disadvantage of the device described in U.S. Pat. No. 519,416 relates to the overall geometry of the described tailpiece with respect to the bridge and saddle structure. The additional proturberances and exposed apertures in the sounding board are undesirable and cumbersome from a functional standpoint and when compared to the proposed invention of this document, it is apparent that the described device is less than desirable if only from an aesthetic standpoint and with regard to the ease of playing the instrument. A comparison of the prior art as described in U.S. Pat. No. 519,416 with the present invention clearly illustrates that the present invention accomplishes independent string suspension, without introduction of distortion sources, by passing the carrier through the sounding board and incorporating it within the saddle structure; and offers a further advantage in the novel method by which precise adjustment of the coupling force between the tuned strings and bridge is achieved.